<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <script type="text/javascript">
            for(var i=1;i<=6;i++){
                document.write("<h"+i+">"+i+"</h"+i+">")
            }
        </script>
    </bodyi
</html>